I continue getting this error following a publish is posted: DATE_FORMAT_COMMENTS | #. Does anybody understand how to fix this?

The truth that the written text is uppercase indicates this becoming an untranslated string used inside the code but that does not match a string within the appropriate language file.

If you're able to locate the right language file you could include the string and it is value directly. Try looking in /languages/en-GB/com_zoo.ini orfor personal files having a similar title in /components/com_zoo/languages/

Alternatively, contact the designers to have an upgrade or fix.